Automatic control for deicing mechanism



Dec. 5, 1939.

L. F. TUMEY AUTOMATIC CONTROL F R DEICING MECHANISM Filed Aug. 10, 1937 INVENTOR. Lawrence ume y RNE Patented Dec. 5, 1939 UNITED STATES AUTOMATIC CDN'IROL FOR DEICI'NG MECHANISM Lawrence F. Tumcy, Baldwin, N. Y., assignor to Eclipse Aviation Corporation,

East Orange,

N. J., a corporation of New Jersey Application August 10,

15 Claims.

This invention relates to aircraft, and more particularly to a means and method for preventing the accumulation of ice on aircraft surfaces, such as the wing and tail structures, the propeller blades, and other exposed surfaces.

It is well known that under certain conditions of temperature and relative humidity,.ice will form on the structural parts of an airplane. This formation is cumulative and at times seriously interferes with the control and operation of aircraft. The more common locations for the ice formation are the leading edges of the wings and tail structure.

In Patent No. 1,998,809 granted to W. C. Geer on April 23, 1935, there is illustrated a type of flexible and expansible overshoe provided upon such leading edges of the wings and tail structures and adapted to expand and contract periodically in response to the operation of pneumatic energizing means.

An object of the present invention is to provide for the automatic initiation of the operation of such overshoe actuating means, so as to relieve the operator of the craft of the necessity of maintaining vigilance to determine the proper moment for bringing such mechanism into operation.

Other objects of the invention will become apparent upon examination of the following description which is to be read in connection with the accompanying drawing illustrating the preferred embodiment of the invention.

In said drawing:

Fig. 1 is a diagrammatic representation of the parts entering into the preferred embodiment of the invention and the electrical operatingconnections therefor;

Fig. 2 is a view in elevation of the moisture and temperature responsive units of the switches controlled thereby;

Fig. 3 is a sectional view through a portion of a .wing or tail structure containing the units shown in Fig. 2; and t Fig. 4 is a view in perspective of the structure shown in Fig. 3, the structure being shown as cut transversely along the line 4-4 of Fig. 3.

Referring to the drawing, reference character I designates an electric device for initiating the operation of theovershoe actuating means, or any equivalent ice dislodging mechanism, and reference character 8 indicates a source of current for supplying the unit 5 with the operating energy required.

Reference character 'I designatesv a switch which maybe manually operated to produce a 1937, Serial No. 158,406

l2 designate ether filled expansible cilia v This framework it also supports the second expansible member l2 which is adapted to expand upon absorption otheat and to contract when cool, the two units i i and i2 being disposed within the air stream confined by the conduit means indicated at H in Figs. 3 and 4, the said conduit having one end thereof projecting through the L wing structure adjacent the leading edge thereof as indicated at E8 and a discharge end near the trailing edge as indicated at iii. A partition 2i is provided longitudinally of the conduit H to separate the air stream into two sections, one to act upon the unit It and the other to act upon the unit I! as indicated. Switch elements are attached to units H and I2 as indicated at and 21 respectively, and are adapted to control energization of an electromagnet 3i which in turn operates upon the set of contacts 32, 33 to produce energization of the unit 5.

Springs or their equivalents are provided for the purpose of allowing over-travel (in a downward direction) of each set of contacts, such a spring for the contacts 42 and 43 being indicated at M, and such a spring for the contacts i8 and 4'! being indicated at 48. A spring tending to hold the contacts 32 and 33 apart is indicated at 4|. Cooperating with the springs 44 and 48 are adjusting means 59 and 52 respectively whereby the extent of movement necessary to produce closure of a circuit through the conducting member 2! is controlled.

Th operation of the system is based upon the known fact that the formation of ice or snow is governed by two factors, namely, temperature and humidity. Both the temperature responsive device i2 and the humidity responsive device ll are however, sensitive to temperature changes but in addition the device H is also sensitive to humidity changes due to the fact that the fabric 13 is maintained in a moist condition by the capillary action of drawing liquid fromthe reservoir ll; hence its temperature is relatively lower than that of the similarly constructed bellows l2, due to the cooling efiect of evaporation from the fabric l3 when the humidity is low. When the amount of moisture in the air increases the rate of evaporation is lower and hence the cooling effect upon the member I l is less. This allows the member H to retain suflicient heat to cause expansion and produce engagement of the con-' tacts 46 and 47. Then if the temperature is at the freezing point resulting contraction of the bellows l2 (due to its more rapid radiation of heat) will have produced a movement of the conducting member 21 downward sufiiciently to close the contact 42 upon the contact 43. This concurrent closure of the contacts 46, 41 and 42, 43 establishes a path for current flow to the relay 3| as indicated clearly in Fig. 1- -assuming of course, that switch I is in engagement with the contact 9. The resulting energization of the relay 3| establishes a circuit to energize the deicing mechanism 5, the circuit passing by way of conductors 55 and 56 and the now closed contacts 32 and 33. The resulting rotation of motor 5 will produce corresponding rotation of the distributor valve 26, and also produces operation of the compressor 23, the latter serving to replenish the supply of compressed air in the reservoir 24, and the former serving to periodically connect said reservoir 24 with each overshoe" or expansible member on the aerofoil surfaces, as described in the Geer patent above identified. Operation of the deicing mechanism will then vcontinue until there is a change of either humidity'or temperature conditions sufficient to open one or the other of the sets of contacts 46, 41 or 42, 43, whereupon the Winding 3i will be de-energized and the spring M will then become effective to re-open contacts 32, 33 and thus restore the parts to the initial non-operating condition.

In addition to its use on aircraft, the invention is also applicable to any air conditioning problem involving exposed surfaces upon which ice might otherwise accumulate.

What I claim is:

1. In an aircraft, deicing mechanism operative at all altitudes for preventing ice accumulation on the exterior surface of said aircraft and for removing such ice as may have formed on said surface, means responsive to ice forming conditions on said aircraft for automatically rendering said deicing mechanism operative, and means for rendering said last named means ineffective at all temperatures above freezing.

2. In an aircraft, deicing mechanism operative at all altitudes for preventing ice accumulation on an exterior convex surface of said aircraft and for removing such ice as may have formed on lation on said surfaces, and means responsive to ice forming conditions for automatically renderin: said first-named means operative under erated means, circuit controlling switch members in said circuit, means normally holding said switch members in open circuit position, moisture responsive means for moving one of said switch members toward the other, temperature responsive means for producing concurrent movement of said second switch member either toward or away from the first switch member, the direction of movement being in accordance with the direction of temperature change, and means including a third switch member for causing said circuit to remain open at all temperatures above freezing, regardless of the amount of movement of said moisture and temperature responsive switch member.

6. The combination, with lifting surfaces of an aircraft, of means for preventing ice accumulation on said surfaces, said means including a source of current and an electric circuit, circuit controlling switch members in said circuit, moisture responsive means for moving one of said switch members toward the other, temperature responsive means for producing concurrent movement of said second switch member either toward or away from the first switch member, the direction of movement being in accordance with the direction of temperature change, and means including a third switch member for causing said circuit to remain open at all temperatures above freezing, regardless of the amount of movement of said moisture and temperature responsive switch members.

7. The combination, with lifting surfaces of an aircraft, of means for preventing ice accumulation on said surfaces, said means including a .source of current and an electric circuit, circuit controlling switch means in said circuit, including a temperature-responsive conducting element, moisture responsive means engageable with one end of said temperature responsive conducting element for shifting the latter independently of any temperature change, and additional conducting means engageable with the opposite end of said temperature responsive conducting element only when the temperature is at or below freezing.

8. The combination, with a source of current and an electric circuit, of circuit controlling switch members in said circuit, moisture responsive means for moving one of said switch members toward the other, temperature responsive means for producing concurrent movement of said second switch member either toward or away from the first switch member, the direction of movement being in accordance with the direction of temperature change, and means including a third switch member for causing said circuit to remain open at all temperatures above freezing, regardless 'of the amount of movement of said moisture and temperature responsive switch members.

9. The combination with a source of current and an electric circuit, of circuit controlling switch means in said circuit, including a temperature responsive conducting element, moisture responsive means engageable with one end of said temperature responsive conducting element for shifting the latter independently of any temperature change, and additional conducting means engageable with the opposite end of said temperature responsive conducting element only when the temperature is at or below freezing.

10. The combination with an ice removin means for aircraft, of a circuit controlling energization t'fiereof, said circuit including a pair of current conducting elements, and means for holding said pair of current conducting elements in engagement, one with the other, at all freezing temperatures.

11. The combination with an ice removing means for aircraft, of a circuit controlling energization thereof, said circuit including a pair of current conducting elements, means for holding said pair of current conducting elements in engagement, one with the other, at all freezing temperatures regardless of the presence or absence 20 of moisture on the craft, and means including a third current conducting element engageable with one of said first named current conducting elements to complete the energization controlling circuit.

12. The combination with an ice removing means for aircraft, of a circuit controlling energization thereof, said circuit including a pair of current conducting elements, means for holding said pair of current conducting elements in en- 30 gagement, one with the other, at all freezing temperatures regardlessof the presence or absence of moisture on the craft, means including a third current conducting element engageable with one of said first named current conducting elements to complete, the energization controlling circuit, and moisture-responsive means for actuating said third current conducting element.

13. The combination with an ice removing means for aircraft, of means for controlling energization of said ice removing means, said lastnamed means including a shiftable control element, and temperature responsive means for holding said control element in a position tending to produce energization of said ice removing means at all freezing temperatures.

14. The combination with an ice removing means for aircraft, of means for controlling energization of said ice removing means, said lastnamed means including a shiftable control element, and temperature responsive means for holding said control element in a position tending to produce energization of said ice removing means at all freezing temperatures and in advance of the actual formation of any considerable amount of ice.

15. The combination with an ice removing means for aircraft, of means for controlling energization of said ice removing means, said lastnamed means including a shiftable control ele-. ment, and means for holding said control element a in a position tending to produce energization of said. ice removing means in advance of the actual formation of any considerable amount of ice.

LAWRENCE F. TUMEY. 

